What is Fosphenytoin?

Fosphenytoin is an anti-epileptic drug, also called an anticonvulsant. It works by slowing down impulses in the brain that cause seizures.
Fosphenytoin is used to prevent or control seizures. Fosphenytoin is used only for a short time, such as 5 days, when other forms of phenytoin cannot be given.
Fosphenytoin may also be used for other purposes not listed in this medication guide.

What is the most important information I should know about Fosphenytoin?

You should not use this medication if you are allergic to fosphenytoin or phenytoin (Dilantin) or if you have certain heart conditions such as slow heartbeats, heart block, AV block, or Adams-Stokes syndrome (a heart rhythm disorder).
Before receiving fosphenytoin, tell your doctor if you are allergic to any drugs, or if you have heart, kidney, or liver disease, low blood pressure, alcoholism, porphyria, or diabetes.
Fosphenytoin may cause harm to an unborn baby, but having a seizure during pregnancy could harm both the mother and the baby. Do not receive fosphenytoin without telling your doctor if you are pregnant. Seizure control is very important during pregnancy and the benefits of preventing seizures may outweigh any risks posed by using fosphenytoin.
If you have received fosphenytoin during pregnancy, be sure to tell the doctor who delivers your baby about your fosphenytoin use. Both you and the baby may need to receive medications to prevent excessive bleeding during delivery and just after birth.
Avoid drinking alcohol while you are receiving fosphenytoin.
There are many other medicines that can interact with fosphenytoin. Tell your doctor about all the prescription and over-the-counter medications you use. This includes vitamins, minerals, herbal products, and drugs prescribed by other doctors. Do not start using a new medication without your doctor’s advice.

What should I discuss with my healthcare provider before taking Fosphenytoin?

You should not receive this medication if you are allergic to fosphenytoin or phenytoin (Dilantin) or if you have certain heart conditions:

• slow heartbeats
• heart block
• AV block; or
• Adams-Stokes syndrome (a heart rhythm disorder)

Before you receive fosphenytoin, tell your doctor if you are allergic to any drugs, or if you have:

• heart disease
• kidney disease
• liver disease
• low blood pressure
• alcoholism
• porphyria; or
• diabetes

If you have any of these conditions, you may need a dose adjustment or special tests to safely receive this medication.
Patients of Asian ancestry may have a higher risk of developing a rare but serious skin reaction to fosphenytoin. Your doctor may recommend a blood test before you start the medication to determine your risk of this skin reaction.
Fosphenytoin can lower your blood sugar. If you are a diabetic, check your blood sugar regularly while you are using this medication.
FDA pregnancy category D. Fosphenytoin may cause harm to an unborn baby, but having a seizure during pregnancy could harm both the mother and the baby. Do not receive fosphenytoin without telling your doctor if you are pregnant. Seizure control is very important during pregnancy and the benefits of preventing seizures may outweigh any risks posed by using fosphenytoin.
If you have received fosphenytoin during pregnancy, be sure to tell the doctor who delivers your baby about your fosphenytoin use. Both you and the baby may need to receive medications to prevent excessive bleeding during delivery and just after birth.
Fosphenytoin can make birth control pills less effective. Avoid pregnancy while receiving fosphenytoin.
It is not known whether fosphenytoin passes into breast milk or if it could harm a nursing baby. Do not use this medication without telling your doctor if you are breast-feeding a baby.

Fosphenytoin Side Effects

What are the possible side effects of Fosphenytoin?

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.
Tell your caregivers at once if you have any of these serious side effects:

• severe itching, burning, numbness, or tingly feeling in your groin or other body areas
• the first sign of any skin rash, no matter how mild
• severe blistering, peeling, and red skin rash
• feeling like you might pass out
• easy bruising or bleeding, unusual weakness
• fever, chills, swollen glands, body aches, flu symptoms
• stomach pain, loss of appetite, dark urine, jaundice (yellowing of the skin or eyes)
• confusion, unusual thoughts or behavior
• extreme thirst or hunger, urinating more than usual
• tremors, or restless muscle movements in your eyes, tongue, jaw, or neck
• slurred speech, loss of balance or coordination; or
• ringing in your ears

Less serious side effects may be more likely to occur, such as:

• dizziness, drowsiness, headache
• nausea, dry mouth; or
• warmth, redness, or tingly feeling under your skin

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Fosphenytoin Interactions

What other drugs affect Fosphenytoin?

Drugs that can increase fosphenytoin levels in your blood include:

• disulfiram (Antabuse)
• birth control pills or hormone replacement therapy
• chlorpromazine (Thorazine), prochlorperazine (Compazine), thioridazine (Mellaril) and other phenothiazines
• methylphenidate (Ritalin, Concerta, Daytrana)
• a barbiturate such as amobarbital (Amytal), butabarbital (Butisol), mephobarbital (Mebaral), secobarbital (Seconal), or phenobarbital (Luminal, Solfoton)
• stomach acid reducers such as cimetidine (Tagamet), ranitidine (Zantac), famotidine (Pepcid), or nizatidine (Axid)
• certain sedatives (such as Librium or Valium) or antidepressants (such as Prozac); or
• sulfa drugs such as Septra or Bactrim

Drugs that can make fosphenytoin less effective in controlling seizures include:

• reserpine; or
• carbamazepine (Tegretol, Epitol, Carbatrol)

Other drugs that can interact with fosphenytoin include:

• a blood thinner such as warfarin (Coumadin)
• digoxin (digitalis, Lanoxin)
• furosemide (Lasix)
• steroid medications (prednisolone and others)
• theophylline (Elixophyllin, Theo-Dur, Theo-Bid, Theolair, Uniphyl)
• valproic acid (Depakene) or divalproex sodium (Depakote)
• an antibiotic such as rifampin (Rimactane, Rifadin, Rifamate) or doxycycline (Doryx, Vibramycin, Adoxa, and others); or
• an antidepressant such as amitriptyline (Elavil), clomipramine (Anafranil), imipramine (Janimine, Tofranil), fluoxetine (Prozac), trazodone (Desyrel), and others

This list is not complete and there are many other medicines that can interact with fosphenytoin. Tell your doctor about all the prescription and over-the-counter medications you use. This includes vitamins, minerals, herbal products, and drugs prescribed by other doctors. Do not start using a new medication without your doctor’s advice.

What should I avoid while taking Fosphenytoin?

Avoid drinking alcohol while you are receiving fosphenytoin. Alcohol use can increase your blood levels of fosphenytoin and may increase side effects. Daily alcohol use can decrease your blood levels of fosphenytoin, which can increase your risk of seizures.

Fosphenytoin Dosage

How should I take Fosphenytoin?

Fosphenytoin is given as an injection into a muscle or through a needle placed into a vein. You will receive this injection in a clinic or hospital setting. Your doctor, nurse, or other healthcare provider will give you this injection.
Your heart rate will be monitored through electrocardiograph or ECG (sometimes called an EKG) when you are given your first dose of fosphenytoin. This machine measures electrical activity of the heart. This will help your doctor determine whether fosphenytoin is causing any harmful effects on your heart.
To be sure this medication is not causing other harmful effects, your blood may need to be tested at regular intervals.

What happens if I overdose on Fosphenytoin?

Seek emergency medical attention if you think you have received too much of this medicine. An overdose of fosphenytoin can be fatal.
Overdose symptoms may include weakness, nausea, vomiting, feeling light-headed, chest pain, fast or slow heart rate, weak pulse, slow breathing (breathing may stop).

What happens if I miss a dose of Fosphenytoin?

Since fosphenytoin is given as needed by a healthcare professional, it is not likely that you will miss a dose.
Sourced from everydayhealth.com